The industrial market depends intensely on wood-based composites for buildings, furniture, and construction, involving significant developments in wood glues since 80% of wood-based products use adhesives. Although biobased glues have been used for many years, notably proteins, they were replaced by synthetic ones at the beginning of the 20th century, mainly due to their better moisture resistance. Currently, most wood adhesives are based on petroleum-derived products, especially formaldehyde resins commonly used in the particleboard industry due to their high adhesive performance. However, formaldehyde has been subjected to strong regulation, and projections aim for further restrictions within wood-based panels from the European market, due to its harmful emissions. From this perspective, concerns about environmental footprint and the toxicity of these formulations have prompted researchers to re-investigate the utilization of biobased materials to formulate safer alternatives. In this regard, proteins have sparked a new and growing interest in the potential development of industrial adhesives for wood due to their advantages, such as lower toxicity, renewable sourcing, and reduced environmental footprint. This work presents the recent developments in the use of proteins to formulate new wood adhesives. Herein, it includes the historical development of wood adhesives, adhesion mechanism, and the current hotspots and recent progress of potential proteinaceous feedstock resources for adhesive preparation.

A comprehensive characterization of the physical and chemical properties of whole duck feathers from French mulard species, including their various categories and fractions (barbs, rachis, and calamus), was conducted to explore potential ways for utilizing this waste product. This analysis aimed to identify opportunities for valorizing these feathers and unlocking their untapped potential. Hence, the duck feathers were thoroughly characterized by a proximate analysis to determine their composition and theoretical heating value. Additionally, feathers underwent other analyses as Sodium Dodecyl Sulfate Polyacrylamide Gel Electrophoresis (SDS-PAGE) analysis, solvent behavior and chemical durability assessment, hydrophobicity testing, Fourier Transform Infrared (FT-IR) spectroscopy, Thermogravimetric Analysis (TGA), Differential Scanning Calorimetry (DSC), X-ray diffraction (XRD), and Scanning Electron Microscopy (SEM). The analyses revealed duck feather composition, molecular weight, stability in different environments, hydrophobicity, functional groups present, thermal behavior, crystallinity, and structural arrangement. Upon analysis, it was determined that duck feathers contain pure fiber keratin and possess characteristics that make them suitable for the production of high-value keratin-based products, including cosmetics, activated carbon for purification, materials for waterproofing, lightweight construction, and textile innovations, underscoring their potential to support sustainable and eco-friendly initiatives across various sectors.

Coffee silverskin, a by-product of coffee processing, was studied using microscopic (SEM), spectroscopic (FTIR), and thermogravimetric (TGA, DSC) methods to assess its use as a substitute filler in the manufacturing of plywood. TGA showed that the material was compatible with plywood hot pressing temperatures (140 °C) and that it was thermally stable up to 50 °C, with a notable decomposition event at 335 °C. Functional groups like hydroxyl and carbonyl were detected by FTIR analysis, indicating possible hydrogen bonds and chemical adaptability. DSC analysis confirmed structural alterations by highlighting endothermic processes associated with dehydration and an exothermic transition over 150 °C. Coffee silverskin substituted rye flour in plywood adhesive compositions at different concentrations (0%, 1%, 5%, 10%, and 20%). Due to the structural and chemical constraints of the filler, larger concentrations (10% and 20%) dramatically lowered bonding strength, whereas low silverskin amounts (1% and 5%) attained strengths equivalent to rye flour, reaching up to 5 N mm⁻², according to internal bond strength tests. SEM images revealed smaller, more fragmented, and porous silverskin particles than larger, compact rye flour particles, which affected mechanical interlocking and adhesion. The findings point to coffee silverskin as an environmentally friendly and performance-balancing substitute for conventional fillers, especially at medium levels.

Global poultry waste production is substantial, with billions of poultry raised annually for meat and egg production, resulting in significant feather waste. Conventional poultry waste disposal methods are restricted due to environmental concerns. Meanwhile, wood-composite panel industries face raw material shortages, emphasizing the need for sustainable, renewable fiber sources. In this study, in the core layer of panels, wood particles were replaced with 5 wt% clean duck feathers without pretreatment to take advantage of feather attributes like hydrophobicity, thermal insulation, and sound damping as an alternative construction material. Three adhesives—urea-formaldehyde (UF), polymeric 4,4′-diphenylmethane diisocyanate (pMDI), and polyvinyl acetate (PVAc)—were examined for resin–feather compatibility. The control panels in this study were identical but wood was not replaced with feathers. The results revealed that wood–feather particleboard with pMDI and PVAc resins meets the requirements of the relevant standard for P2 boards (where applicable) concerning their modulus of rupture (MOR: 11 N·mm⁻²), modulus of elasticity (MOE: 1600 N·mm⁻²), internal bond (IB: 0.35 N·mm⁻²), and screw withdrawal resistance (SWR). However, those produced with UF resin did not meet the standards for IB and MOE. Furthermore, the physical properties showed similar water resistance and thickness swelling to control panels with pMDI. Notably, substituting 5 wt% wood with feathers improved thermal insulation by approximately 10% for UF and pMDI resins. Additionally, particleboard with feathers demonstrated improved sound absorption at high frequencies, ranging from 2500 to 500 Hz, particularly with pMDI resin, approaching Class B classification according to EN ISO 11654:1997. This study identifies the higher compatibility of pMDI over PVAc and UF adhesives for feather-based composite materials in construction applications.